there are some reports about the amino acid L-theanine blocking the action of caffeine in certain brain areas. It is not commonly found in too many food sources (some mushrooms, green tea) but can purchased at some vitamin stores.

I took some a couple months ago after a long day of cafe crawling followed by cupping followed by more cupping. The next morning as I was walking to work I experienced a small migraine which is peculiar and has scared me off from further experimentation with L-theanine. I will give it a whirl again with less of a caffeine overdose. Your mileage may vary and if you google it or search PubMed there are probably a number of references.

It would be interesting if something claimed to block caffeine. The last theory I read is that caffeine blocks adenosine sits, adenosine being a hormone that calms the body down, lowers body temp, metabolism etc.

If something were blocking caffeine wouldn't it also block the adenosine?